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calorie/hr to watts convertion....(4 posts)

calorie/hr to watts convertion....Bruno S
Mar 14, 2003 2:47 PM
there is a stationary bike at the gym that displays calories/hr. Anyone knows how to convert this value into watts?
re: calorie/hr to watts convertion....Continental
Mar 14, 2003 3:14 PM
The stationary bike displays estimated Calories (actually kilocalories) per hour burned. The bike is measuring the power you are applying to it, then back calculating an estimate of calories burned using some equation that estimates your efficiency. You are probably interested in useful watts (work/time) that you are applying to the bike. It is easy to convert Kilocalories/hr to watts--simply multiply Kcal/hr times 1.16 to get watts. However, this would give you an estimate of the watts you are burning, not the watts of useful work/time that you are performing. Unless you know the equation that the bike uses to estimate your efficiency, you won't be able to calculate the useful power in watts that you are applying to the bike. I use a lot of different excercise bikes at various hotels and gyms. Many display both watts and calories/hr, but they use different estimates for calories per hour.
re: calorie/hr to watts convertion....cyclopathic
Mar 16, 2003 4:45 AM
human efficiency on bike is ~20-25%. While it will be hard to tell expect number due to many variables (training, straps, body position, temperature, airflow, load etc) the easiest way to approximate power output is to take Cal output and divide it by 4.
Don't pay a lot of attention to itSprint-Nick
Mar 15, 2003 9:09 PM
With this said I'm not saying don't pay attention to it. If you use it properly it could be a good benchmark of how much energy your producing during a ride. But as Conti said its showing you how many watts/calories are being used and not how many are being produced. Theres a big difference there. Then since its geared towards someone who rides a heck of a lot less than you my understanding is your numbers of calories burnt/watts produced will be less than the number stated.

Ultimately if you really want to see your wattage you need to get an SRM, Powertap or Polar HRM + power sensor which is a lot of $$$. But if you perhaps try recording your calories burnt and time then do a calorie per minute calculation? This is something you can compare easily if your using the same bike all the time.

Cheers,
Nick
PodiumBound.ca